W.L.P. Bredie and M.A. Petersen (Editors) Flavour Science: Recent Advances and Trends © 2006 Elsevier B.V. All rights reserved. Formation of methyl (methylthio)methyl disulfide in broccoli (Brassica oleracea (L.) var. italica) Jean-Claude Spadone, Walter Matthey-Doret and Imre Blank Nestle Research Center, Vers-chez-les-Blanc, 1000 Lausanne 26, Switzerland ABSTRACT Vapour cooking of fresh broccoli did not generate 2,3,5-trithiahexane (TTH) but cutting broccoli into pieces followed by cooking in water allowed the detection of this odorant. The formation of TTH was enhanced upon frozen storage of cut broccoli pieces for a few weeks. Cutting broccoli activates cysteine sulfoxide lyase transforming methylcysteine sulfoxide into methylsulfenic acid, which upon heating gives rise to dimethyl sulfide and dimethyl bisulfide that react to TTH. Thus, enzymatic reactions combined with thermal treatment may favour TTH formation. 1. INTRODUCTION Vegetables belonging to the Brassica species (e.g. white cabbage and broccoli) are widely used in fresh or frozen form in home-style culinary preparations and industrial products. Methyl (methylthio)methyl disulfide, also referred to as 2,3,5-trithiahexane (TTH), has been reported as an unusual constituent of broccoli, cabbage, and cauliflower [1,2], besides methanethiol (MT) and dimethyl trisulfide (DMTS) as well- known volatile compounds of Brassicaceae. The sensory properties of TTH were described as garlic-like, alliaceous, sulfury, and cooked cabbage-like [2-4] with a recognition odour threshold of 40 ppb in water [5]. TTH has been suggested as a character impact compound significantly contributing to the typical flavour of various plants such as such as Brassica pekinensis [2], Hua gabonii ('garlic plant'), [3], Marasmius alliaceus [4] and Scorodocarpus borneensis ('wood garlic') [5]. In the present work, the formation of TTH in broccoli was investigated, in particular the role of enzymatic reactions and thermal treatment in developing the freshly cooked broccoli character. The sensory significance of TTH was also addressed.